The invention generally relates to a device for providing a seal between a shaft and a housing. In particular, the invention relates to a dynamic, metallic labyrinth seal device for preventing lubricant from leaking out of a housing and/or for preventing contaminants from traveling into the housing. The invention also relates to a labyrinth seal device capable of functioning in high temperature environments. The invention also relates to a method of assembling a sealed system.
Prior art devices for sealing a rotating shaft are disclosed in U.S. Pat. No. 4,022,479 (Orlowski) and U.S. Pat. No. 5,024,451 (Borowski). Seal devices of this type may be used to prevent lubricant from escaping out of a bearing housing and/or to prevent contaminants from working their way into the housing. The prior art devices are formed of at least two ring-shaped members that rotate with respect to each other when the shaft is rotated. One of the members is fixed to the housing and does not rotate. The other member rotates with the rotating shaft.
The two ring members should be located very close together, particularly when the seal device is used to isolate the bearing from small particulate contaminants. Even small quantities of such contaminants are capable of significantly deteriorating the bearing. To prevent such contamination, the two relatively rotatable ring members must be held together very closely, with only a very narrow space therebetween.
The ring members of the Orlowski seal device are connected together by a separate securing means. The ring members themselves have no means for establishing and maintaining a narrow spacing therebetween. Therefore, the Orlowski seal device cannot be manufactured as a unit with a preset, fixed spacing. The spacing between the ring members has to be set when the seal device is installed into the housing. This leaves room for human error outside the control of the device manufacturer. In particular, the Orlowski device can be improperly installed, with the ring members located too far apart to perform satisfactorily. Another problem with the Orlowski device is that the ring members may be separated subsequent to installation, for example by high pressure cleaning spray.
The ring members of the Borowski device are held together by a bead and a groove provided on the ring members themselves. The bead fits within the groove with an interference fit. This arrangement is an improvement over the Orlowski system in the sense that no separate securing means is needed. But the Borowski device is still unsatisfactory because the bead must be resiliently deformed to be positioned within the groove, and the groove must be correspondingly enlarged to receive the deformed bead. The deformation of the bead during assembly makes it difficult to achieve the desired close positioning between the two ring members. Further, the Borowski device, which incorporates three members, is unsatisfactory for having a greater number of potential leakage paths than seal devices utilizing only two members.
Prior art devices do not disclose unitized labyrinth seals which are capable of operating in high temperature environments, such as during fires. Conventional seal devices composed of TEFLON(copyright) or other similar material, when exposed to high temperatures, may warp, deform or disintegrate, causing a failure in the device to dynamically seal.
The disadvantages of the prior art are alleviated to a great extent by the present invention which provides a metallic seal device including a rotor and a stator having a plastically deformable unitizing element.
In a preferred embodiment of the present invention, the plastically deformable unitizing element is located on the stator and is made to plastically deform radially outwardly to interlock the stator and rotor.
In one aspect of the present invention, the rotor has an annular protrusion to aid in the labyrinth sealing effect and the seal may be a severe splash type seal.
In another preferred embodiment, the unitizing element of the stator plastically deforms radially inwardly and the stator may contain an annular protruding element to add to the labyrinth sealing effect.
In another preferred embodiment, the unitizing element is located on the rotor which interlocks into a recess located in the stator.
Another object of the present invention is to use the metallic plastically deformable unitizing element to create a seal which can be used as an internal baffle to control the movement of fluid contaminant.